I wonder how planet glows are done in Hegemonia ? I am able to create a good looking glow but the authors managed to fade it so it is only visible over the parts which are exposed to star radiation.

Here are some pics:

http://www.republika.pl/enmaniac/images/Haegemonia_000.jpg

http://www.republika.pl/enmaniac/images/Haegemonia_001.jpg

http://www.republika.pl/enmaniac/images/Haegemonia_002.jpg

Does anyone know how to perform such a thing ?
Thx

Brolingstanz

11-05-2005, 12:10 PM

looks like basic glow to me.

i don't see the need to post 3 huge images to convey a basic concept like this, particularly in the advanced forum.

btw, the clouds strike me as a bit out of place. are the planets transparent? the rings aren't lit...

zzzzz....

enmaniac

11-05-2005, 04:26 PM

yes it seems to be a 'basic' glow but still I have no idea how the effect can be achieved

I dont care about the image size as far as it shows the concept, especially in advanced forum but I downsampled them anyway. I am not native english speaker (writter) and I wasnt sure whether I explained the prob clear enough

why do you think the planets are transparent ? I cannot see any transparency on them (nor I could see it on the bigger images). Yes the rings arent lit and are even transparent.

zed

11-05-2005, 05:06 PM

btw, the clouds strike me as a bit out of placefrom a cursory glance i thought they were nebula
but since u mention + looked and yes they are clouds, dont know why (maybe the wine) but it brought tears to my eyes

anyways OP one way to achieve that glow would be to redraw the planet again (is it a texture) slightly enlarged with some sort of blur + a slight additive blend

AlexN

11-05-2005, 10:08 PM

I would draw a ring around the planet, orientated like a billboard. Use the vector from the center of the planet to each vertex as the normal, and apply the same lighting from the planet to the ring, to make it fade out along the dark side of the planet. Doing this with additive blending will probably get you want you are looking for.

rgpc

11-06-2005, 04:18 AM

The first image shows that they are using additive blending and applying it after the rings are drawn (the "glow" of the planet brightens the rings).

IMO the more you look at the images, the worse the effect is (ie. the clouds, the rings, the lighting).

Brolingstanz

11-07-2005, 02:46 AM

i'd have to agree. notice the false glow in the first image, near the poles and heading into the dark side. this may not be a blur/bloom kind of glow after all, but something far simpler, like the billboard idea alex had, or some other simple approximation.

suffice it to say that you could do a lot better with today's hardware. look at some of the atmospheric rendering techniques out there, where air density and other physical factors are brought into play. try to simulate the physical reality of it, to some extent, instead of trying to fudge it. and get some light on the rings, shadows too. this could look really cool if pampered a bit.

the dark side cloud-city lights make saturn look transparent, to me. it doesn't seem reasonable that that much light should permeate a gas giant's atmosphere. nasa's nighttime shuttle flyovers capture this effect, but only in very clear areas, and with a bit of zoom. there's a kind of shimmer to it, very cool. then again, maybe they're not cities at all, and i've imagined the whole thing. perhaps they're satellites, launched by the saturnians in an effort to waste as much energy as possible by beaming blinding light into the cosmos...

by the by, what the heck does all this have to do with opengl? and while we're off topic, why can't i sit around in my underwear my entire life, and play games? (rhetorical)

FanThomaS

11-10-2005, 01:53 AM

Originally posted by enmaniac:
Hi all!

I wonder how planet glows are done in Hegemonia ? Does anyone know how to perform such a thing ?
ThxHi,

That's an good, old hungarian game :)
Yes I know, how they did that: Do you know how fur rendering working ? They used the same idea for "glowing".